/**
 * Copyright 2010 The Apache Software Foundation
 *
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.UUID;
import java.util.regex.Pattern;

import org.apache.hadoop.hbase.ipc.HRegionInterface;
import org.apache.hadoop.hbase.util.Bytes;

/**
 * HConstants holds a bunch of HBase-related constants
 */
public final class HConstants {
	/**
	 * Status codes used for return values of bulk operations.
	 */
	public enum OperationStatusCode {
		NOT_RUN, SUCCESS, SANITY_CHECK_FAILURE, FAILURE;
	}

	/** long constant for zero */
	public static final Long ZERO_L = Long.valueOf(0L);
	public static final String NINES = "99999999999999";
	public static final String ZEROES = "00000000000000";

	// For migration

	/** name of version file */
	public static final String VERSION_FILE_NAME = "hbase.version";

	/**
	 * Current version of file system.
	 * Version 4 supports only one kind of bloom filter.
	 * Version 5 changes versions in catalog table regions.
	 * Version 6 enables blockcaching on catalog tables.
	 * Version 7 introduces hfile -- hbase 0.19 to 0.20..
	 */
	// public static final String FILE_SYSTEM_VERSION = "6";
	public static final String FILE_SYSTEM_VERSION = "7";

	// Configuration parameters

	//TODO: Is having HBase homed on port 60k OK?

	/** Cluster is in distributed mode or not */
	public static final String CLUSTER_DISTRIBUTED = "hbase.cluster.distributed";

	/** Config for pluggable load balancers */
	public static final String HBASE_MASTER_LOADBALANCER_CLASS = "hbase.master.loadbalancer.class";

	/** Cluster is standalone or pseudo-distributed */
	public static final boolean CLUSTER_IS_LOCAL = false;

	/** Cluster is fully-distributed */
	public static final boolean CLUSTER_IS_DISTRIBUTED = true;

	/** Default value for cluster distributed mode */
	public static final boolean DEFAULT_CLUSTER_DISTRIBUTED = CLUSTER_IS_LOCAL;

	/** default host address */
	public static final String DEFAULT_HOST = "0.0.0.0";

	/** Parameter name for port master listens on. */
	public static final String MASTER_PORT = "hbase.master.port";

	/** default port that the master listens on */
	public static final int DEFAULT_MASTER_PORT = 60000;

	/** default port for master web api */
	public static final int DEFAULT_MASTER_INFOPORT = 60010;

	/** Parameter name for the master type being backup (waits for primary to go inactive). */
	public static final String MASTER_TYPE_BACKUP = "hbase.master.backup";

	/** by default every master is a possible primary master unless the conf explicitly overrides it */
	public static final boolean DEFAULT_MASTER_TYPE_BACKUP = false;

	/** Name of ZooKeeper quorum configuration parameter. */
	public static final String ZOOKEEPER_QUORUM = "hbase.zookeeper.quorum";

	/** Name of ZooKeeper config file in conf/ directory. */
	public static final String ZOOKEEPER_CONFIG_NAME = "zoo.cfg";

	/** Common prefix of ZooKeeper configuration properties */
	public static final String ZK_CFG_PROPERTY_PREFIX = "hbase.zookeeper.property.";

	public static final int ZK_CFG_PROPERTY_PREFIX_LEN = ZK_CFG_PROPERTY_PREFIX.length();

	/**
	 * The ZK client port key in the ZK properties map. The name reflects the
	 * fact that this is not an HBase configuration key.
	 */
	public static final String CLIENT_PORT_STR = "clientPort";

	/** Parameter name for the client port that the zookeeper listens on */
	public static final String ZOOKEEPER_CLIENT_PORT = ZK_CFG_PROPERTY_PREFIX + CLIENT_PORT_STR;

	/** Default client port that the zookeeper listens on */
	public static final int DEFAULT_ZOOKEPER_CLIENT_PORT = 2181;

	/** Parameter name for the wait time for the recoverable zookeeper */
	public static final String ZOOKEEPER_RECOVERABLE_WAITTIME = "hbase.zookeeper.recoverable.waittime";

	/** Default wait time for the recoverable zookeeper */
	public static final long DEFAULT_ZOOKEPER_RECOVERABLE_WAITIME = 10000;

	/** Parameter name for the root dir in ZK for this cluster */
	public static final String ZOOKEEPER_ZNODE_PARENT = "zookeeper.znode.parent";

	public static final String DEFAULT_ZOOKEEPER_ZNODE_PARENT = "/hbase";

	/**
	 * Parameter name for the limit on concurrent client-side zookeeper
	 * connections
	 */
	public static final String ZOOKEEPER_MAX_CLIENT_CNXNS = ZK_CFG_PROPERTY_PREFIX + "maxClientCnxns";

	/** Parameter name for the ZK data directory */
	public static final String ZOOKEEPER_DATA_DIR = ZK_CFG_PROPERTY_PREFIX + "dataDir";

	/** Default limit on concurrent client-side zookeeper connections */
	public static final int DEFAULT_ZOOKEPER_MAX_CLIENT_CNXNS = 300;

	/** Configuration key for ZooKeeper session timeout */
	public static final String ZK_SESSION_TIMEOUT = "zookeeper.session.timeout";

	/** Default value for ZooKeeper session timeout */
	public static final int DEFAULT_ZK_SESSION_TIMEOUT = 180 * 1000;

	/** Parameter name for port region server listens on. */
	public static final String REGIONSERVER_PORT = "hbase.regionserver.port";

	/** Default port region server listens on. */
	public static final int DEFAULT_REGIONSERVER_PORT = 60020;

	/** default port for region server web api */
	public static final int DEFAULT_REGIONSERVER_INFOPORT = 60030;

	/** A flag that enables automatic selection of regionserver info port */
	public static final String REGIONSERVER_INFO_PORT_AUTO = "hbase.regionserver.info.port.auto";

	/** Parameter name for what region server interface to use. */
	public static final String REGION_SERVER_CLASS = "hbase.regionserver.class";

	/** Parameter name for what region server implementation to use. */
	public static final String REGION_SERVER_IMPL = "hbase.regionserver.impl";

	/** Default region server interface class name. */
	public static final String DEFAULT_REGION_SERVER_CLASS = HRegionInterface.class.getName();

	/** Parameter name for what master implementation to use. */
	public static final String MASTER_IMPL = "hbase.master.impl";

	/** Parameter name for how often threads should wake up */
	public static final String THREAD_WAKE_FREQUENCY = "hbase.server.thread.wakefrequency";

	/** Default value for thread wake frequency */
	public static final int DEFAULT_THREAD_WAKE_FREQUENCY = 10 * 1000;

	/** Parameter name for how often we should try to write a version file, before failing */
	public static final String VERSION_FILE_WRITE_ATTEMPTS = "hbase.server.versionfile.writeattempts";

	/** Parameter name for how often we should try to write a version file, before failing */
	public static final int DEFAULT_VERSION_FILE_WRITE_ATTEMPTS = 3;

	/** Parameter name for how often a region should should perform a major compaction */
	public static final String MAJOR_COMPACTION_PERIOD = "hbase.hregion.majorcompaction";

	/** Parameter name for HBase instance root directory */
	public static final String HBASE_DIR = "hbase.rootdir";

	/** Parameter name for HBase client IPC pool type */
	public static final String HBASE_CLIENT_IPC_POOL_TYPE = "hbase.client.ipc.pool.type";

	/** Parameter name for HBase client IPC pool size */
	public static final String HBASE_CLIENT_IPC_POOL_SIZE = "hbase.client.ipc.pool.size";

	/** Parameter name for HBase client operation timeout, which overrides RPC timeout */
	public static final String HBASE_CLIENT_OPERATION_TIMEOUT = "hbase.client.operation.timeout";

	/** Default HBase client operation timeout, which is tantamount to a blocking call */
	public static final int DEFAULT_HBASE_CLIENT_OPERATION_TIMEOUT = Integer.MAX_VALUE;

	/** Used to construct the name of the log directory for a region server
	 * Use '.' as a special character to seperate the log files from table data */
	public static final String HREGION_LOGDIR_NAME = ".logs";

	/** Used to construct the name of the splitlog directory for a region server */
	public static final String SPLIT_LOGDIR_NAME = "splitlog";

	public static final String CORRUPT_DIR_NAME = ".corrupt";

	/** Like the previous, but for old logs that are about to be deleted */
	public static final String HREGION_OLDLOGDIR_NAME = ".oldlogs";

	/** Used to construct the name of the compaction directory during compaction */
	public static final String HREGION_COMPACTIONDIR_NAME = "compaction.dir";

	/** Conf key for the max file size after which we split the region */
	public static final String HREGION_MAX_FILESIZE = "hbase.hregion.max.filesize";

	/** Default maximum file size */
	public static final long DEFAULT_MAX_FILE_SIZE = 10 * 1024 * 1024 * 1024L;

	/**
	 * The max number of threads used for opening and closing stores or store
	 * files in parallel
	 */
	public static final String HSTORE_OPEN_AND_CLOSE_THREADS_MAX = "hbase.hstore.open.and.close.threads.max";

	/**
	 * The default number for the max number of threads used for opening and
	 * closing stores or store files in parallel
	 */
	public static final int DEFAULT_HSTORE_OPEN_AND_CLOSE_THREADS_MAX = 1;

	/** Conf key for the memstore size at which we flush the memstore */
	public static final String HREGION_MEMSTORE_FLUSH_SIZE = "hbase.hregion.memstore.flush.size";

	/** Default size of a reservation block   */
	public static final int DEFAULT_SIZE_RESERVATION_BLOCK = 1024 * 1024 * 5;

	/** Maximum value length, enforced on KeyValue construction */
	public static final int MAXIMUM_VALUE_LENGTH = Integer.MAX_VALUE;

	/** name of the file for unique cluster ID */
	public static final String CLUSTER_ID_FILE_NAME = "hbase.id";

	/** Configuration key storing the cluster ID */
	public static final String CLUSTER_ID = "hbase.cluster.id";

	// Always store the location of the root table's HRegion.
	// This HRegion is never split.

	// region name = table + startkey + regionid. This is the row key.
	// each row in the root and meta tables describes exactly 1 region
	// Do we ever need to know all the information that we are storing?

	// Note that the name of the root table starts with "-" and the name of the
	// meta table starts with "." Why? it's a trick. It turns out that when we
	// store region names in memory, we use a SortedMap. Since "-" sorts before
	// "." (and since no other table name can start with either of these
	// characters, the root region will always be the first entry in such a Map,
	// followed by all the meta regions (which will be ordered by their starting
	// row key as well), followed by all user tables. So when the Master is
	// choosing regions to assign, it will always choose the root region first,
	// followed by the meta regions, followed by user regions. Since the root
	// and meta regions always need to be on-line, this ensures that they will
	// be the first to be reassigned if the server(s) they are being served by
	// should go down.

	/** The root table's name.*/
	public static final byte[] ROOT_TABLE_NAME = Bytes.toBytes("-ROOT-");

	/** The META table's name. */
	public static final byte[] META_TABLE_NAME = Bytes.toBytes(".META.");

	/** delimiter used between portions of a region name */
	public static final int META_ROW_DELIMITER = ',';

	/** The catalog family as a string*/
	public static final String CATALOG_FAMILY_STR = "info";

	/** The catalog family */
	public static final byte[] CATALOG_FAMILY = Bytes.toBytes(CATALOG_FAMILY_STR);

	/** The regioninfo column qualifier */
	public static final byte[] REGIONINFO_QUALIFIER = Bytes.toBytes("regioninfo");

	/** The server column qualifier */
	public static final byte[] SERVER_QUALIFIER = Bytes.toBytes("server");

	/** The startcode column qualifier */
	public static final byte[] STARTCODE_QUALIFIER = Bytes.toBytes("serverstartcode");

	/** The lower-half split region column qualifier */
	public static final byte[] SPLITA_QUALIFIER = Bytes.toBytes("splitA");

	/** The upper-half split region column qualifier */
	public static final byte[] SPLITB_QUALIFIER = Bytes.toBytes("splitB");

	/**
	 * The meta table version column qualifier.
	 * We keep current version of the meta table in this column in <code>-ROOT-</code>
	 * table: i.e. in the 'info:v' column.
	 */
	public static final byte[] META_VERSION_QUALIFIER = Bytes.toBytes("v");

	/**
	 * The current version of the meta table.
	 * Before this the meta had HTableDescriptor serialized into the HRegionInfo;
	 * i.e. pre-hbase 0.92.  There was no META_VERSION column in the root table
	 * in this case.  The presence of a version and its value being zero indicates
	 * meta is up-to-date.
	 */
	public static final short META_VERSION = 0;

	// Other constants

	/**
	 * An empty instance.
	 */
	public static final byte[] EMPTY_BYTE_ARRAY = new byte[0];

	/**
	 * Used by scanners, etc when they want to start at the beginning of a region
	 */
	public static final byte[] EMPTY_START_ROW = EMPTY_BYTE_ARRAY;

	/**
	 * Last row in a table.
	 */
	public static final byte[] EMPTY_END_ROW = EMPTY_START_ROW;

	/**
	  * Used by scanners and others when they're trying to detect the end of a
	  * table
	  */
	public static final byte[] LAST_ROW = EMPTY_BYTE_ARRAY;

	/**
	 * Max length a row can have because of the limitation in TFile.
	 */
	public static final int MAX_ROW_LENGTH = Short.MAX_VALUE;

	/** When we encode strings, we always specify UTF8 encoding */
	public static final String UTF8_ENCODING = "UTF-8";

	/**
	 * Timestamp to use when we want to refer to the latest cell.
	 * This is the timestamp sent by clients when no timestamp is specified on
	 * commit.
	 */
	public static final long LATEST_TIMESTAMP = Long.MAX_VALUE;

	/**
	 * Timestamp to use when we want to refer to the oldest cell.
	 */
	public static final long OLDEST_TIMESTAMP = Long.MIN_VALUE;

	/**
	 * LATEST_TIMESTAMP in bytes form
	 */
	public static final byte[] LATEST_TIMESTAMP_BYTES = Bytes.toBytes(LATEST_TIMESTAMP);

	/**
	 * Define for 'return-all-versions'.
	 */
	public static final int ALL_VERSIONS = Integer.MAX_VALUE;

	/**
	 * Unlimited time-to-live.
	 */
	//  public static final int FOREVER = -1;
	public static final int FOREVER = Integer.MAX_VALUE;

	/**
	 * Seconds in a week
	 */
	public static final int WEEK_IN_SECONDS = 7 * 24 * 3600;

	//TODO: although the following are referenced widely to format strings for
	//      the shell. They really aren't a part of the public API. It would be
	//      nice if we could put them somewhere where they did not need to be
	//      public. They could have package visibility
	public static final String NAME = "NAME";
	public static final String VERSIONS = "VERSIONS";
	public static final String IN_MEMORY = "IN_MEMORY";

	/**
	 * This is a retry backoff multiplier table similar to the BSD TCP syn
	 * backoff table, a bit more aggressive than simple exponential backoff.
	 */
	public static int RETRY_BACKOFF[] = { 1, 1, 1, 2, 2, 4, 4, 8, 16, 32 };

	public static final String REGION_IMPL = "hbase.hregion.impl";

	/** modifyTable op for replacing the table descriptor */
	public static enum Modify {
		CLOSE_REGION, TABLE_COMPACT, TABLE_FLUSH, TABLE_MAJOR_COMPACT, TABLE_SET_HTD, TABLE_SPLIT
	}

	/**
	 * Scope tag for locally scoped data.
	 * This data will not be replicated.
	 */
	public static final int REPLICATION_SCOPE_LOCAL = 0;

	/**
	 * Scope tag for globally scoped data.
	 * This data will be replicated to all peers.
	 */
	public static final int REPLICATION_SCOPE_GLOBAL = 1;

	/**
	 * Default cluster ID, cannot be used to identify a cluster so a key with
	 * this value means it wasn't meant for replication.
	 */
	public static final UUID DEFAULT_CLUSTER_ID = new UUID(0L, 0L);

	/**
	 * Parameter name for maximum number of bytes returned when calling a
	 * scanner's next method.
	 */
	public static String HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE_KEY = "hbase.client.scanner.max.result.size";

	/**
	 * Maximum number of bytes returned when calling a scanner's next method.
	 * Note that when a single row is larger than this limit the row is still
	 * returned completely.
	 *
	 * The default value is unlimited.
	 */
	public static long DEFAULT_HBASE_CLIENT_SCANNER_MAX_RESULT_SIZE = Long.MAX_VALUE;

	/**
	 * Parameter name for client pause value, used mostly as value to wait
	 * before running a retry of a failed get, region lookup, etc.
	 */
	public static String HBASE_CLIENT_PAUSE = "hbase.client.pause";

	/**
	 * Default value of {@link #HBASE_CLIENT_PAUSE}.
	 */
	public static long DEFAULT_HBASE_CLIENT_PAUSE = 1000;

	/**
	 * Parameter name for maximum retries, used as maximum for all retryable
	 * operations such as fetching of the root region from root region server,
	 * getting a cell's value, starting a row update, etc.
	 */
	public static String HBASE_CLIENT_RETRIES_NUMBER = "hbase.client.retries.number";

	/**
	 * Default value of {@link #HBASE_CLIENT_RETRIES_NUMBER}.
	 */
	public static int DEFAULT_HBASE_CLIENT_RETRIES_NUMBER = 10;

	/**
	 * Parameter name for maximum attempts, used to limit the number of times the
	 * client will try to obtain the proxy for a given region server.
	 */
	public static String HBASE_CLIENT_RPC_MAXATTEMPTS = "hbase.client.rpc.maxattempts";

	/**
	 * Default value of {@link #HBASE_CLIENT_RPC_MAXATTEMPTS}.
	 */
	public static int DEFAULT_HBASE_CLIENT_RPC_MAXATTEMPTS = 1;

	/**
	 * Parameter name for client prefetch limit, used as the maximum number of regions
	 * info that will be prefetched.
	 */
	public static String HBASE_CLIENT_PREFETCH_LIMIT = "hbase.client.prefetch.limit";

	/**
	 * Default value of {@link #HBASE_CLIENT_PREFETCH_LIMIT}.
	 */
	public static int DEFAULT_HBASE_CLIENT_PREFETCH_LIMIT = 10;

	/**
	 * Parameter name for number of rows that will be fetched when calling next on
	 * a scanner if it is not served from memory. Higher caching values will
	 * enable faster scanners but will eat up more memory and some calls of next
	 * may take longer and longer times when the cache is empty.
	 */
	public static String HBASE_META_SCANNER_CACHING = "hbase.meta.scanner.caching";

	/**
	 * Default value of {@link #HBASE_META_SCANNER_CACHING}.
	 */
	public static int DEFAULT_HBASE_META_SCANNER_CACHING = 100;

	/**
	 * Parameter name for unique identifier for this {@link org.apache.hadoop.hbase.conf.Configuration}
	 * instance. If there are two or more {@link org.apache.hadoop.hbase.conf.Configuration} instances that,
	 * for all intents and purposes, are the same except for their instance ids,
	 * then they will not be able to share the same {@link org.apache.hadoop.hbase.client.HConnection} instance.
	 * On the other hand, even if the instance ids are the same, it could result
	 * in non-shared {@link org.apache.hadoop.hbase.client.HConnection}
	 * instances if some of the other connection parameters differ.
	 */
	public static String HBASE_CLIENT_INSTANCE_ID = "hbase.client.instance.id";

	/**
	 * HRegion server lease period in milliseconds. Clients must report in within this period
	 * else they are considered dead. Unit measured in ms (milliseconds).
	 */
	public static String HBASE_REGIONSERVER_LEASE_PERIOD_KEY = "hbase.regionserver.lease.period";

	/**
	 * Default value of {@link #HBASE_REGIONSERVER_LEASE_PERIOD_KEY}.
	 */
	public static long DEFAULT_HBASE_REGIONSERVER_LEASE_PERIOD = 60000;

	/**
	 * timeout for each RPC
	 */
	public static String HBASE_RPC_TIMEOUT_KEY = "hbase.rpc.timeout";

	/**
	 * Default value of {@link #HBASE_RPC_TIMEOUT_KEY}
	 */
	public static int DEFAULT_HBASE_RPC_TIMEOUT = 60000;

	/*
	 * cluster replication constants.
	 */
	public static final String REPLICATION_ENABLE_KEY = "hbase.replication";
	public static final String REPLICATION_SOURCE_SERVICE_CLASSNAME = "hbase.replication.source.service";
	public static final String REPLICATION_SINK_SERVICE_CLASSNAME = "hbase.replication.sink.service";
	public static final String REPLICATION_SERVICE_CLASSNAME_DEFAULT = "org.apache.hadoop.hbase.replication.regionserver.Replication";

	/** HBCK special code name used as server name when manipulating ZK nodes */
	public static final String HBCK_CODE_NAME = "HBCKServerName";

	public static final ServerName HBCK_CODE_SERVERNAME = new ServerName(HBCK_CODE_NAME, -1, -1L);

	public static final String KEY_FOR_HOSTNAME_SEEN_BY_MASTER = "hbase.regionserver.hostname.seen.by.master";

	public static final String HBASE_MASTER_LOGCLEANER_PLUGINS = "hbase.master.logcleaner.plugins";

	public static final String HBASE_REGION_SPLIT_POLICY_KEY = "hbase.regionserver.region.split.policy";

	/**
	 * Configuration key for the size of the block cache
	 */
	public static final String HFILE_BLOCK_CACHE_SIZE_KEY = "hfile.block.cache.size";

	public static final float HFILE_BLOCK_CACHE_SIZE_DEFAULT = 0.25f;

	/*
	  * Minimum percentage of free heap necessary for a successful cluster startup.
	  */
	public static final float HBASE_CLUSTER_MINIMUM_MEMORY_THRESHOLD = 0.2f;

	public static final List<String> HBASE_NON_USER_TABLE_DIRS = new ArrayList<String>(Arrays.asList(new String[] {
			HREGION_LOGDIR_NAME, HREGION_OLDLOGDIR_NAME, CORRUPT_DIR_NAME, Bytes.toString(META_TABLE_NAME),
			Bytes.toString(ROOT_TABLE_NAME), SPLIT_LOGDIR_NAME }));

	public static final Pattern CP_HTD_ATTR_KEY_PATTERN = Pattern.compile("^coprocessor\\$([0-9]+)$", Pattern.CASE_INSENSITIVE);
	public static final Pattern CP_HTD_ATTR_VALUE_PATTERN = Pattern
			.compile("(^[^\\|]*)\\|([^\\|]+)\\|[\\s]*([\\d]*)[\\s]*(\\|.*)?$");

	public static final String CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN = "[^=,]+";
	public static final String CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN = "[^,]+";
	public static final Pattern CP_HTD_ATTR_VALUE_PARAM_PATTERN = Pattern.compile("(" + CP_HTD_ATTR_VALUE_PARAM_KEY_PATTERN
			+ ")=(" + CP_HTD_ATTR_VALUE_PARAM_VALUE_PATTERN + "),?");

	/** The delay when re-trying a socket operation in a loop (HBASE-4712) */
	public static final int SOCKET_RETRY_WAIT_MS = 200;

	/** Host name of the local machine */
	public static final String LOCALHOST = "localhost";

	/** Enable file permission modification from standard hbase */
	public static final String ENABLE_DATA_FILE_UMASK = "hbase.data.umask.enable";
	/** File permission umask to use when creating hbase data files */
	public static final String DATA_FILE_UMASK_KEY = "hbase.data.umask";

	/** 
	 * If this parameter is set to true, then hbase will read
	 * data and then verify checksums. Checksum verification 
	 * inside hdfs will be switched off.  However, if the hbase-checksum 
	 * verification fails, then it will switch back to using
	 * hdfs checksums for verifiying data that is being read from storage.
	 *
	 * If this parameter is set to false, then hbase will not
	 * verify any checksums, instead it will depend on checksum verification
	 * being done in the hdfs client.
	 */
	public static final String HBASE_CHECKSUM_VERIFICATION = "hbase.regionserver.checksum.verify";

	/**
	 * The name of the configuration parameter that specifies
	 * the number of bytes in a newly created checksum chunk.
	 */
	public static final String BYTES_PER_CHECKSUM = "hbase.hstore.bytes.per.checksum";

	/**
	 * The name of the configuration parameter that specifies
	 * the name of an algorithm that is used to compute checksums
	 * for newly created blocks.
	 */
	public static final String CHECKSUM_TYPE_NAME = "hbase.hstore.checksum.algorithm";

	/** Configuration name of HLog Compression */
	public static final String ENABLE_WAL_COMPRESSION = "hbase.regionserver.wal.enablecompression";

	private HConstants() {
		// Can't be instantiated with this ctor.
	}
}
